AQA D2 2013 January — Question 8

Exam BoardAQA
ModuleD2 (Decision Mathematics 2)
Year2013
SessionJanuary
TopicNetwork Flows

8 The network below represents a system of pipes. The capacity of each pipe, in litres per second, is indicated on the corresponding edge.
\includegraphics[max width=\textwidth, alt={}, center]{3ba973a1-6a45-4381-b634-e9c4673ef1fb-22_743_977_404_536}
  1. Find the maximum flow along each of the routes \(A B E H , A C F H\) and \(A D G H\) and enter their values in the table on Figure 4 opposite.
    1. Taking your answers to part (a) as the initial flow, use the labelling procedure on Figure 4 to find the maximum flow through the network. You should indicate any flow-augmenting routes in the table and modify the potential increases and decreases of the flow on the network.
    2. State the value of the maximum flow and, on Figure 5 opposite, illustrate a possible flow along each edge corresponding to this maximum flow.
  2. Confirm that you have a maximum flow by finding a cut of the same value. List the edges of your cut. \begin{table}[h]
    \captionsetup{labelformat=empty} \caption{Figure 4}
    RouteFlow
    \(A B E H\)
    \(A C F H\)
    \(A D G H\)
    \end{table} \begin{figure}[h]
    \captionsetup{labelformat=empty} \caption{Figure 4} \includegraphics[alt={},max width=\textwidth]{3ba973a1-6a45-4381-b634-e9c4673ef1fb-23_746_972_397_845}
    \end{figure} \begin{figure}[h]
    \captionsetup{labelformat=empty} \caption{Figure 5} \includegraphics[alt={},max width=\textwidth]{3ba973a1-6a45-4381-b634-e9c4673ef1fb-23_739_971_1311_539}
    \end{figure}
    \includegraphics[max width=\textwidth, alt={}]{3ba973a1-6a45-4381-b634-e9c4673ef1fb-24_2253_1691_221_153}